RFR: 8333849: (dc) DatagramChannel send/receive fails with UOE if buffer backed by memory segment allocated from shared arena

[Alan Bateman]

DatagramChannel send/receive throw UOE if invoked with a ByteBuffer that is backed by a memory segment allocated from a shared arena.  These methods don't use IOUtil so was missed when the new accessor to get the buffer address was added. The issue is a remainder of lack of test coverage so I've added a test that exercises all read/write methods in the ByteChannel implementations.

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/19618/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19618&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8333849
  Stats: 509 lines in 2 files changed: 506 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/19618.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19618/head:pull/19618

PR: https://git.openjdk.org/jdk/pull/19618